Fashion Photography - Inclusion of Shadows (How the brain perceives an image) (under construction)

I want to focus a lot on lighting, to include shadows and contrast across a subject, like this:

The way the light falls on the subject draws attention to the head a shoulders area even though it is 3/4 shot.

I also like the use of shadows to give more depth to the photo, like this:

To me the addition of the shadow to this photo gives it a more 3d feel. The brain plays a major part in understanding the 3d world we live in, most people presume that we see in 3d because we have two eyes spaced a small distance apart and these two images combined produces a 3d image. In some ways this is true but at any considerable distance the angle of the eyes is so small that there lines of sight are practically parallel, therefore the brain has to rely on experience to understand what it is looking at. One of the major factors of understanding the 3d world is shadows, the size and orientation of a shadow in relation to the subject lets the brain determine distance, shape and size, for this reason I feel it is important to include shadows in a photo because the image produced is 2d there is no chance that the eyes can do the work of making it appear 3d it must be the way the brain perceives the image, therefore the inclusion of shadows will let the brain perceive the image in a more 3d manner. The one thing to remember is that the image is never actually 3d it is just the brains perception of 3d.